The excuse the MD police are using to justify these .50 caliber rifles is as an anti-vehicle weapon. They say in an article that it could be used to stop a runaway truck full of explosives used by a terrorist.
I think the police in MD are watching to many action movies...
Also, I would like ANYONE in the LE community to give a single example of a "runaway truck full of explosives" used in a terrorist incident ANYWHERE in the industrialized world. As a general rule, terrorists who use truck bombs park them in front of their target, walk away to a safe distance, and then detonate them remotely. The IRA was famous for this.
And even if you believe the "official story" of Oklahoma City, that truck was parked, unoccupied, in front of the Alfred P. Murrah Building for 5 minutes before it was detonated. (of course, we have no idea how long the demolition charges INSIDE the building that caused the internal structural damage to the rear opposite corner of the building, or the charges in the front that blew structural elements across the street--TOWARD and OVER the truck--were in place...)
And although a .50BMG can cause catastrophic damage to the engine block of such a truck, a "runaway truck" would have enough momentum that even with a disabled engine, it would be able to travel hundreds of feet without power, if put into neutral by the driver.
I think we all know the REAL reason that MD LEOs think they need .50 caliber sniper rifles, and it's not for bearded men who live in caves in the desert.
It's for people like some of the folks on this forum, when the trains start rolling and the camps open up...